This invention relates to phenol-formaldehyde resin foam systems. More particularly, it relates to a method of obtaining a phenolformaldehyde foam system which requires the admixture together of only two components.
The major use of this foam system is as an insulating material in building construction due to its low flammability and good insulation properties.
Most foam systems, of which polyurethanes are perhaps the best known, are obtained by cross linking a polymer by means of a catalyst, in the presence of a blowing agent. It is the blowing agent which forms the gas which causes the system to foam. This gas can be generated in several ways. It can be obtained chemically, but the most used method, perhaps because it is inherently the simplest, is to incorporate into the foam system a low boiling compound which is liquid under normal storage conditions for the foam components, which does not interfere with the cross linking reaction, but which vapourizes under the influence of heat generated in that cross linking reaction. It is also necessary that the foaming agent be dispersible, preferably soluble, in one of the components used to make the foam. The commonly used blowing agents are low boiling hydrocarbons such as butane and pentane, or chlorofluoro hydrocarbons, such as dichlorodifluoromethane.
Thus, it is apparent that the basic needs which must be met to get a good foam are proper cross linkable resin, a catalyst capable of cross linking that resin, and a blowing agent. It is also apparent that to prepare foam, one simply has to mix together these three reagents, together with desired surfactant, inert dyes, fillers, plasticizers and so forth.
The difficulty that this invention seeks to solve in relation to phenol-formaldehyde foam is that this simple picture bears only a limited similarity to reality. Clearly it is most convenient for the user to be able to prepare a foam by taking the requisite amounts of two components out of their containers, mixing thoroughly, and waiting. For many of the industrially used systems, particularly the urethane systems, this is the situation. But where phenol-formaldehyde systems are concerned, it is not that simple case. The difficulty that has been encountered with phenol-formaldehyde systems has been that it has not been possible hitherto to produce a stable, storable material capable of packaging in simple containers with an adequate shelf life which contains in only two components the three major requirements of catalyst, phenol-formaldehyde resin, and blowing agent.